1. Field of the Invention
This invention relates to a filter device for separating blood fractions.
2. Description of the Prior Art
In the examination of blood samples by one method coagulation is caused and the coagulated blood is separated by centrifugalizing in a tube into the specifically heavier and non-filtratable gel-like blood cake on the one hand and the liquid, specifically lighter filtratable blood serum on the other hand. The desired examinations are then performed with the serum, and in doing so it has to be observed that no red blood cells pass into the serum fraction from the blood cake, since these would disturb or even render impossible the examinations.
For other examinations on the other hand a blood coagulation is prevented by adding appropriate coagulation obstructing substances, and the blood is separated by precipitation or centrifugalizing into the specifically heavier fraction of the red blood cells and the specifically lighter blood plasma. The desired examinations are then performed with the blood plasma, and again the entry of blood cells into the blood plasma must be prevented, since otherwise the examinations would be disturbed.
In both instances, i.e. in the yielding of blood serum as well as in the yielding of blood plasma, the specifically lighter fraction required for the examination has up to now been taken by means of a pipette from the upper portion of the tube containing the two fractions. In case this work is not done very carefully, red blood cells pass from the specifically heavier fraction into the pipette and then generally render the sample taken unusable. The work of the separation of the specifically lighter blood fraction to be tested, therefore, requires some care and is time consuming.